Tube



Sept. 20, 1932. J KERR 1,878,242

TUBE

Original Filed Nov. 10, 1928 2 Sheets-Sheet l ATTORN EYS.

Sept. 20, 1932. ER 1,878,242

TUBE

Original Filed Nov. 10, 1928 2 Sheets-Sheet 2 INVENTOR Howard J. KerrATI'ORN EY Patented Sept. 20, 1932 UNITED STATES PATENT OFFICE HOWARDil'. KERR, OF WESTFIELD, NEW JERSEY, ASSIGNOR TO THE BAIBCOOK & WIL- COXCOMPANY, OF BAYONNE, NEW JERSEY, A CORPORATION OF NEW JERSEY TUBE.lpplication filed November 10, 1928, Serial no. 318,351. RenewedDecember 12,1931.

Figs. 2, 4, 6, 8 and 10 are fragmentary.

longitudinal views of tubes, partly in elevation and partly in section,showing different forms which the invention may take.

.Figs. 3, 5, 7 and 9 are views taken on the lines 33, 55,'77 and 99respectively, of Figs. 2, .4, 6 and 8 respectively.

In places wheretubes, particularly metallic tubes, are used to receiveheat at their outer surfaces and transmit this heat to a fluid pass ingthrough the tubes,.it has been found that the heat can be absorbed atthe outer surface faster than itcan betransmitted from the inner surfaceto the fluid. This situation steam or water flowing through the tubes.

In Fig. 1, I have shown my improved form of tube used in a radiant heatsuperheater comprising inlet and outlet headers 1 and metallic tubes 2,the tubes being disposed in the walls 3 of a furnace heated by apulverized fuel burner 4. Above the furnace be placed the boiler 5 Iiiorder to approximately equalize the rate of heatabsorption by the outersurfaces of the tubes and the rate of heat transmission by the innersurfaces to the fl-uid in the tubes, I decrease the extent of the outermetallic surface of the tubes. This may bedone by integrally securingrefractory material to thetubes. y

In Figs. 2 to 10 inclusive, I have illustrated different ways in whichthe refractory material may be secured to the tubes.

In Figs. 2 and 3, I have shown a tube 2 provided with a helical grooveor recess 6 which may have at least one wall 7 undercut as shown, tofirmly hold the refractory mate rial 8 inv place. If desired, this wallmay be made without the undercut feature, but this arrangement. forms aconvenient means. for holding the parts together. If desired, the

wall or walls of the groove may be roughened as indicated at 9, to aidin binding the refractory material to the metal of the tube. In thisform ofthe invention, the refractory material is preferably put on in aplastic condition, although it may be previously prepared in sectionsand cemented to the tube.

In Figs. 2 and 3, the refractory material is shown as approximatelyfilling the groove, so that its outer surface is substantially flushwith the normal outer surface of the tube. In Figs. 4 and 5, a similararrangement is shown, but one in which the refractory material is madethicker, soas to form,'with the metal of'the tube, a thicker wall. Thisarrangement may be preferable for some situations. In Figs. 6 and 7 isshown an embodiment in which the outer surface of the tube is providedwith a plurality of spaced recesses 'which are substantially round incross-sec tion. These recesses arepreferablyformed, as shown, so thatthe metal not removed in making them constitutes continuouscircumferential projections. The wall of each recess may besubstantially cylindrical, or ma be undercut, as shown. This wall may aso be rovided with the roughened portions 10, i desired. The refractorymaterial may be' 'tion placed in the recesses in a plastic con or may bepreformed and cemented in place. In either case, it will be seen thatthe result is a plurality of buttons 11 of refractory material forming apart of the outer surface of the tube, with portions of the metallicsurface therebetween, thesurface of the buttons being substantiallyflush with that of the .metallic outer surface of the tube.

In Figs. 8 and. 9 are shown buttons-12, similar to the buttons 11,except that they project outwardly from the metallic surface of the.tube and thus form a relatively greater surface of refractory materialwith respect to the metallic surface.

'In Fig. '10 is shown a modification of the arrangement of Figs. 8 and9, the buttons being united to form a substantially contin uous outersurface 13 of refractory material.

In this form, the material is preferably put in place in a plasticcondition. While I have shown a continuous outer surface, it is to beunderstood that if desired, a tube may be provided for a portion of itssurface with the arrangement of Figs. 8 and 9, and for another portionwith the form of Fig. 10.

I claim 1. A metallic tube having outer and inner surfaces and adaptedto receive heat at the outer surface and transmit it to a fluid passingthrough the tube, said outer surface having a plurality of spacedsubstantially cylindrical recesses therein, and buttons ofrefractorymaterial disposed in said recesses.

2. In a tubular heat exchanger adapted as a part of a furnace wall totransmit to a contained fluid the heat received radiantly from fuelburning in the mace; said tubular heat exchanger having a metallic innerpart in contact with the contained fluid; and a composite outerstructure exposed to radiant heat from the burning fuel; said outerstruc-' ture comprising a continuous body of metal projecting from theinner part and constituting circumferentially arranged metallic spacers,and refractory materials contacting with the inner part and locatedbetween the spacers, said refractory materials being of greater thermalresistance than the material of the remaining structure, therebypreventing overheating of the exchanger metal and contributing to higherfurnace temperaturesr 3. In a tubular heat exchanger adapted as a partof a furnace wall to transmit to a contained fluid the heat receivedradiantly from fuel burning in the furnace; said tubular heat exchangerhaving a metallic inner part in contact with the contained fluid; and acomposite outer structure exposed to radiant heat from the burning fuel;said outer structure comprising a continuous body of metal projectingfrom the inner part and circumferentially arranged with reference to theinner part and constituting metallic projections; and refractorymaterial contacting with the innr part and located between theprojections, said refractory material being of greater thermalresistance than the material of the remaining structure, therebypreventing overheating of the exchanger metal and contributing to higherfurnace temperatures.

4. In a tubular heat exchanger adapted as a part of a furnace wall totransmit to a contributing to higher furnace temperatures.

HOWARD J. KERR.

contained fluid the heat received radiantly from fuel burning in thefurnace; said tubular heat exchanger having a metallic inner part incontact with the contained fluid; and a composite outer structureexposed to radiant heat from the burning fuel; said outer structurecomprising a circumferentially arranged continuous body of metalprojecting from the inner part and constituting metallic projections,and refractory material contacting with the inner part and locatedbetween

